 <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
    <div id="app">
        <input type="number" v-model.number="number_one">
        <select v-model="operation" @change="yunsuan()">
            <option value="">请选择加减乘除</option>
            <option value="+">+</option>
            <option value="-">-</option>
            <option value="*">*</option>
            <option value="/">/</option>
        </select>
        <input type="number" v-model.number="number_two">
        <p>{{suan}}</p>
    </div>
    <script>
        new Vue({
            el: '#app',
            data: {
                num1: 0,
                num2: 0,
                operation: '',
                result: 0
            },
            methods: {
                yunsuan: function () {
                    if (this.operation === '+') {
                        this.suan = this.number_one + this.number_two
                    } else if (this.operation === '-') {
                        this.suan = this.number_one - this.number_two
                    } else if (this.operation === '*') {
                        this.suan = this.number_one * this.number_two
                    } else if (this.operation === '/') {
                        this.suan = this.number_one / this.number_two
                    } else {
                        this.suan = 0
                    }
                }
            }
        })
    </script>